Which One?

[bust]

Let's see what your made of Kong

 

[Mekong]

3 and 4 at the same time

[bust]

I was thinking 3 due to the hydraulic effects of the low feed from from 4 into 3. The pressure is greater than the high feed to 4. That make sense

[Coss]

Depends on flow of the tap, if the flow is great enough, 1. If those are the last four drops from the tap, 'cause it's off, then none.

[bust]

Also if the flow of the tap is greater than the drain to 2 then 1 will fill first.

[pe7e]

Assuming the flow is as illustrated (very slow) tank 3 will fill first (just)

[Coss]

But really, none, as its just a collection of 1s and 0s that my computer has interpreted and displayed on my monitor as a picture, water won't flow, no, won't go, you'll have to post a video for any of this to work

[Mekong]

I was thinking 3 due to the hydraulic effects of the low feed from from 4 into 3. The pressure is greater than the high feed to 4. That make sense

 

Once the level in Vessel 3 is at same height as its outlet pipe the pressure in 3 and 4 will be identical and as such both vessels act as one

 

That would cause level in Vessel 2 to increase above its Outlet causing 3 and 4 to increase at the same rate.

 

Being pedantic like Pe7e Vessel 3 will theoretically be full first due to the "Process Lag" imposed on the system by the interconnecting pipe between vessel 3 and 4 but that would be measured in yoctoseconds ys (10^-24)

 

So theoretically it would be Vessel 3 but impossible to see or measure so to all intents and purposes 3 and 4 at same time

[pe7e]

I concur, but fluid dynamics being what they are ie water doesn't flow particularly fast, it wouldn't be measured in yoctoseconds ys (10^-24)

[Mekong]

I concur

 

I'm glad someone understood